1. Field of Invention
This invention pertains to a mechanism for moving a shower head used to clean a paper web in a papermaking machine, and more particularly to a machine with a motorized shower head moving along a stationary track.
2. Description of the Prior Art
In a papermaking machine, it is frequently necessary to rewet the paper web using a shower head. In addition, the various forming, dryer fabrics and press felts are also cleaned with a water jet to remove various foreign particles and/or to rebulk the felt or fabric. In order to insure a uniform coverage by the jet, the shower head is moved or oscillated in a reciprocal motion across the width of the web, felt or fabric. To this end the shower head is coupled to a stationary motor by a standard sprocket-and-chain arrangement. However this type of arrangement has been found to be unreliable because of frequent breakdown. In addition, under certain conditions it is desirable to direct the shower automatically to a particular zone. However, such an operation is difficult to perform with shower heads oscillated by a sprocket-and-chain because the exact location of the head at any particular moment cannot be precisely determined.
A further problem with the prior art shower head mechanism occurs when the shower head hangs up in an arbitrary location, while the motor and chain are still moving. As a result, the water jet is directed towards a single zone of paper web, fabric or felt and by the time this condition is noticed by an operator, the web, fabric or felt are frequently damaged.